如何使用麦克风从麦克风/线路输入进行FFT

Question

我正在尝试计算来自麦克风输入的某些声音的FFT。 FFT是使用Python的Numpy计算的。当我使用保存的wave文件时，它已经可以工作了。现在，我要使用来自麦克风输入的数据进行此操作。

文件fft.py

import numpy as np
from struct import unpack

power = []

# Return power array index corresponding to a particular frequency
def piff(val, sample_rate, chunk):
   return int(4 * chunk * val/sample_rate)


def calculate_levels(matrix, weighting, data, chunk, sample_rate):
   # Convert raw data (ASCII string) to numpy array
   data = unpack("%dh"%(len(data)/2),data)
   data = np.array(data, dtype='h')

   # Apply FFT - real data
   fourier = np.fft.rfft(data)

   # Remove last element in array to make it the same size as chunk
   fourier = np.delete(fourier, len(fourier) - 1)

   # Find average 'amplitude' for specific frequency ranges in Hz
   power = np.abs(fourier)

   lower_bound = 0
   upper_bound = 32
   for i in range(len(matrix)):
       mean = np.mean(power[piff(lower_bound, sample_rate, chunk) : piff(upper_bound, sample_rate, chunk):1])
       matrix[i] = int(mean) if np.isnan(mean) == False else 0

       lower_bound = upper_bound
       upper_bound = upper_bound << 1

   # Tidy up column values for the LED matrix
   matrix = np.multiply(matrix, weighting)

   # Set all values smaller than first argument to 0, all greater than second argument to 4095
   matrix = matrix.clip(0, 4095) 
   return matrix

我的calculate_levels函数的输出是具有一定频率水平的矢量。

文件myprogram.py：

import argparse
import socket
import time
import alsaaudio
import wave
import decoder
import sys
import os
import numpy
from fft import calculate_levels

# Initialize the FFT matrix
matrix    = [0, 0, 0, 0, 0, 0, 0, 0]
weighting = [512, 256, 1024, 1024, 2048, 4096, 4096, 4096]

# Precalculate weighting matrix
weighting = numpy.true_divide(weighting, 1000000)

# Set up audio
# args.chunk is 512
# args.sample_rate is 44100 
inp = alsaaudio.PCM(alsaaudio.PCM_CAPTURE, alsaaudio.PCM_NORMAL)
inp.setchannels(2)
inp.setrate(args.sample_rate)
inp.setformat(alsaaudio.PCM_FORMAT_S16_LE)
inp.setperiodsize(args.chunk)

out = alsaaudio.PCM(alsaaudio.PCM_PLAYBACK, alsaaudio.PCM_NORMAL)
out.setchannels(2)
out.setrate(args.sample_rate)
out.setformat(alsaaudio.PCM_FORMAT_S16_LE)
out.setperiodsize(args.chunk)

# Store the recorded audio in a file
w = wave.open('test.wav', 'w')
w.setnchannels(2)
w.setsampwidth(2)
w.setframerate(args.sample_rate)

# Process audio file   
print "Listening..."

while True:
    l, data = inp.read()
    matrix = calculate_levels(matrix, weighting, data, args.chunk, args.sample_rate)

    # Do something with the spectrum ...

    # Go on reading the music file
    out.write(data)

    # Save
    w.writeframes(data)

不幸的是，我收到以下错误：

File "fft.py", line 13, in calculate_levels
    data = unpack("%dh"%(len(data)/2),data)
struct.error: unpack requires a string argument of length 2048

如何避免此错误？

更新：这是当我将某些打印命令放入calculate_levels方法中时的输出：

   print type(data)
   print data
   data = unpack("%dh"%(len(data)/2),data)
   print type(data)
   print data
   data = np.array(data, dtype='h')

输出

<type 'str'>
F9FFDi8480:CED2EE}`&89  9B9E  E6B3CEi
// and some more unreadable values


<type 'tuple'>
(-7, 3908, 2153, 2948, 1920, 1338, 462, 2258, 494, 3965, 1632, 4134, 2441, 3227, 2462, 2022, 947, 1230, -1175, 1942, -528, 2771, 1296, 894, -243, -1598, -2106, -1121, -856, -18, -507, -1664, -2082, -3105, -2045, -1497, -1101, -146, -721, -1675, -1027, -3448, -2358, -2581, -1954, -779, 293, -955, -199, -1962, -2096, -1719, -1497, -1170, -719, -980, -879, -503, -265, 65, 311, 611, 101, 825, -335, 493, -482, 1092, 574, 1927, 1006, 1044, -688, 521, -1455, 1179, -589, 559, -873, -331, -1506, 11, -1134, 639, -1190, 1307, -1239, 1581, -707, 1556, 195, 2611, 1751, 3189, 2523, 2508, 1693, 2991, 1555, 4211, 2555, 4153, 2669, 3332, 2111, 2187, 1426, 1120, 501, 773, 352, 836, 476, 459, -775, -1248, -2499, -2067, -2338, -588, -1038, -1271, -1423, -3376, -2563, -1127, -1387, 796, -513, -1740, -1918, -1997, -1538, -450, -112, -1896, -1712, -1518, -2252, 1556, 636, 1574, 1365, 17, -468, 336, -606, 2116, 701, 3832, 1914, 3565, 2623, 2620, 2080, 3725, 1456, 4205, 1560, 2905, 1057, 2416, 193, 1880, 121, 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4156, 1911, 5216, 1519, 3989, 1147, 2849, 1358, 3308, 1145, 1860, -354, -90, -1164, 767, -734, 945, -1206, -1201, -2302, -1662, -2264, -577, -1992, -1073, -1869, -2345, -2065, -2178, -2923, -1219, -2819, -1362, -1499, -1976, -1311, -2017, -1982, -2464, -1834, -2060, -883, -258, 79, -754, -372, -2562, -1399, -1170, -210, 395, 1048, -507, -241, -443, -851, 356, 246, 123, 195, 183, -607, 337, -903, 150, -1327, 441, -1231, 572, -499, 674, -423, 1551, -529, 2183, 133, 2516, 884, 2731, 906, 2331, 937, 2644, 1644, 4033, 2440, 4428, 2367, 3390, 1729, 2417, 1231, 2223, 1011, 1937, 484, 833, -494, 617, -650, 1476, 59, 769, -417, -778, -1411, -781, -912, -480, -712, -975, -1637, -1033, -1523, -1097, -601, -1588, -328, -1538, -601, -1795, -1523, -3066, -2779, -3254, -2178, -2106, -605, -2174, -810, -2857, -1665, -1680, -1182, -449, -630, -749, -825, -642, -627, 9, -464, 636, -195, 1932, 902, 2333, 1033, 1535, -35, 2300, 411, 3107, 1353, 2289, 987, 2584, 1496, 3974, 2716, 4104, 2275, 3897, 1689, 4442, 2549, 5094, 3206, 5257, 2981, 4773, 2414, 4837, 2278, 5167, 2544, 3814, 1760, 2408, 280, 2810, 147, 2558, 251, 606, -984, -732, -1954, -816, -1769, -915, -1615, -1429, -2093, -2005, -2778, -2630, -2809, -3413, -2374, -3565, -2589, -2903, -3151, -2586, -2852, -2967, -2414, -3221, -2722, -3115, -2872, -2553, -2606, -2052, -2442, -1730, -1908, -1136, -1098, -444, -930, -40, -1171, 381, -928, 904, -440, 1359, 94, 1888, 572, 2441, 1008, 2942, 1270, 2845, 1021, 2705, 814, 3665, 1272, 4378, 1739, 4148, 1783, 4456, 1900, 4824, 1817, 4273, 1601, 4245, 2154, 5118, 2913, 5252, 2778, 3910, 1981, 2359, 1672, 2515, 2066, 3134, 2586, 1955, 1907, 69, 27, -581, -914, -299, 240, -723, 407, -2513, -2092, -3197, -3232, -1843, -1812, -1800, -1545, -2818, -2252, -2573, -1905, -2648, -1957, -3196, -2083, -2637, -1456, -2684, -1795, -3012, -2071, -2503, -1044, -2809, -1145, -3131, -2067, -2137, -1361, -1347, -242, -589, 0, 283, 77, 239, -24, 714, 509, 1792, 1859, 2001, 1993, 2407, 995, 3220, 1271, 3698, 2584, 4424, 3153, 4830, 2989, 4504, 2616, 4761, 2324, 5039, 2379, 4840, 2616, 5108, 2793, 5526, 3092, 5287, 2673, 4604, 1520, 3841, 1024, 3127, 950, 2299, 167, 1802, -453, 1637, -834, 534, -1987, -763, -2817, -895, -2820, -1194, -3118, -2027, -3514, -2400, -3645, -2975, -3705, -3058, -3004, -2114, -1850, -2460, -2179, -3865, -3417, -4033, -3303, -3425, -2323, -3101, -1990, -2887, -2073, -2729, -2246, -2435, -2633, -2194, -2490, -2099, -1757, -1358, -1348, -373, -1032, 77, -534, 480, -372, 657, -287, 804, -39, 1687, 351, 2263, 922, 1908, 853, 2099, 200, 3010, 621, 3591, 1314, 3832, 847, 3980, 744, 4071, 1294, 4480, 1412, 4892, 1510, 4662, 1504, 4194, 1566, 4246, 2331, 3926, 2134, 2694, 1042, 1698, 902, 923, 559, -140, -558, -374, -484, -479, -473, -2060, -1858, -3301, -2478, -2781, -2294, -2574, -2611, -3138, -2509, -2994, -1950, -2509, -1773, -2460, -1740, -2396, -1440, -1900, -951, -1573, -658, -1791, -903, -1656, -1068, -999, -769, -974, -773, -1078, -714, -210, -272, 408, 123, 130, 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1354, 756, 1733, 904, 1802, 711, 2034, 30, 2391, -106, 2543, 332, 3023, 508, 3721, 654, 3515, 566, 2633, -74, 2492, -122, 2920, 559, 3028, 706, 2597, 279, 1878, -28, 1429, -252, 1694, -70, 2172, 526, 2054, 601, 1758, 331, 1983, 546, 2001)


<type 'str'>
86aEAO    (CF
// and some more unreadable values

<type 'tuple'>
(902, 1889, 1002, 2383, 1320, 2767, 1674, 2298, 1553, 1815, 1237, 1434, 834, 839, 153, 199, -387, -526, -419, -1433, -784, -2398, -2047, -3160, -2961, -2947, -2812, -2373, -2321, -2718, -1907, -2965, -1642, -2377, -1601, -2156, -1632, -1940, -1735, -1260, -1348, -1038, -448, -749, -255, 32, -557, 501, -318, 989, -189, 1678, -43, 1849, 456, 1927, 337, 2421, 77, 2654, 870, 2304, 845, 2132, 66, 2681, 739, 2964, 1319, 1927, 396, 1043, 194, 1280, 858, 1467, 906, 1561, 841, 1802, 710, 1261, 267, 551, 194, 878, 191, 1602, 26, 1842, 265, 1453, 430, 692, 127, 64, -464, -250, -1231, -484, -1379, -777, -868, -1332, -1316, -1746, -2051, -2099, -2036, -2851, -2387, -3324, -2989, -2957, -2930, -2508, -3092, -2369, -3130, -2065, -2100, -1138, -1350, -311, -1497, -15, -922, 802, 417, 1890, 1341, 2348, 1924, 2945, 2464, 3668, 2737, 3369, 2969, 3364, 3162, 3895, 2806, 3379, 2427, 3025, 2474, 3499, 2190, 3027, 1812, 2228, 1602, 2284, 859, 1976, 56, 1299, 83, 754, 146, 81, -475, -525, -1112, -945, -1366, -1146, -1409, -1004, -1404, -1231, -1374, -1625, -1144, -1170, -695, -655, -232, -504, 155, 75, 557, 639, 976, 535, 997, 220, 511, -65, 366, 120, 579, 686, 433, 278, -237, -591, -1160, -804, -1728, -1072, -1896, -1448, -2328, -991, -2671, -210, -2114, 64, -1671, -87, -1848, 74, -1748, 701, -1264, 1089, -598, 1158, 96, 1727, 517, 2286, 777, 2296, 1115, 2453, 1522, 2842, 2213, 2997, 2826, 2989, 2951, 2898, 3105, 2785, 3151, 2593, 2658, 1807, 2356, 1493, 2531, 1569, 1930, 510, 455, -408, -77, -155, -50, -826, -1286, -1735, -2532, -1259, -2232, -1061, -2052, -1915, -2880, -2013, -3146, -1328, -2713, -792, -2428, -489, -2069, -66, -1240, 365, -322, 381, 55, 7, -426, -195, -921, -194, -723, -261, -354, -592, -269, -969, -569, -1077, -927, -1239, -907, -1384, -1000, -937, -1329, -625, -1422, -570, -1293, 168, -810, 1250, 270, 2027, 965, 2850, 944, 3355, 1173, 3834, 1743, 4796, 2293, 5440, 2734, 5296, 2861, 4907, 2555, 4573, 2121, 4211, 1733, 3618, 1199, 2904, 749, 2411, 393, 1521, -335, 369, -1250, -161, -1611, -597, -1748, -1392, -2189, -1844, -2479, -2205, -2638, -2914, -3052, -3164, -2915, -2785, -2222, -2470, -1957, -2308, -1724, -1962, -1137, -1414, -827, -1138, -535, -620, 262, 627, 1151, 1495, 1738, 1204, 1795, 946, 1595, 1277, 1768, 1737, 1980, 1913, 1742, 1587, 1462, 1000, 802, 584, -191, 457, -443, 613, -232, 741, -791, 1021, -1352, 1524, -1310, 1510, -1363, 1381, -1400, 2064, -828, 2617, -203, 2465, -11, 2519, -6, 2557, 104, 2303, 578, 2267, 1172, 2009, 1641, 1456, 1889, 962, 1485, 402, 757, -124, 428, -488, 395, -1039, -41, -1577, -678, -1913, -1324, -2513, -2129, -3391, -2800, -3902, -3159, -3861, -3415, -3463, -3397, -2896, -2819, -2450, -2162, -2269, -1905, -1948, -1767, -1363, -1397, -1004, -867, -578, -152, 460, 761, 1394, 1666, 1741, 2027, 1988, 1952, 2067, 1861, 2087, 1811, 2347, 1610, 2367, 1386, 2211, 1377, 2278, 1344, 2258, 800, 2026, 332, 1980, 195, 2066, 36, 2134, 98, 2385, 685, 2820, 1129, 2898, 1095, 2511, 1075, 2590, 1283, 3015, 1465, 2589, 1456, 1802, 1029, 1573, 432, 1291, 238, 805, 298, 623, 66, 356, -408, -478, -852, -1465, -1479, -2088, -2090, -2141, -2022, -1989, -1751, -2343, -2153, -3078, -2973, -3457, -3331, -3282, -3359, -3001, -3084, -2937, -2826, -2651, -2905, -2042, -2543, -1580, -1551, -1283, -883, -575, -628, 428, -4, 1491, 1093, 2368, 2074, 2859, 2600, 3173, 2864, 3532, 3194, 4036, 3281, 4541, 3493, 4583, 3844, 4097, 3315, 3497, 2216, 3048, 1952, 3122, 2063, 3312, 1710, 2772, 1244, 2054, 889, 1781, 421, 1706, 169, 1796, 375, 1764, 432, 1273, 208, 790, -87, 394, -624, -179, -1451, -283, -1601, -150, -1022, -754, -1073, -1616, -1945, -2346, -2648, -3020, -2867, -3256, -2853, -3346, -2843, -3734, -2892, -3932, -2900, -3985, -3083, -4205, -3230, -4072, -3082, -3693, -2981, -3175, -2670, -2571, -1801, -1777, -1019, -744, -484, 400, 295, 1122, 1095, 1640, 1772, 2532, 2435, 3610, 2863, 4126, 3171, 4141, 3432, 4350, 3333, 4523, 2866, 4372, 2566, 4365, 2378, 4098, 1805, 3432, 1146, 3256, 1029, 2963, 674, 2154, -295, 1889, -635, 1911, -409, 1499, -757, 1246, -1285, 1064, -1354, 852, -1096, 963, -909, 1043, -874, 1114, -490, 1345, 193, 952, 98, 215, -263, -90, 86, -158, 324, -341, 155, -945, 55, -1621, -304, -1754, -700, -1942, -631, -2445, -852, -2382, -1361, -2021, -1422, -2106, -1551, -2294, -2046, -2314, -2325, -1843, -2247, -1203, -2055, -1128, -1942, -889, -2252, -312, -2569, 42, -1966, 804, -961, 1802, -424, 2164, -148, 2491, 242, 3170, 718, 3543, 1335, 3927, 2068, 4565, 2873, 4801, 3471, 4667, 3519, 4329, 3176, 3708, 3001, 3219, 2899, 2880, 2474, 2174, 1879, 1313, 1377, 591, 742, -119, -94, -773, -605, -1139, -876, -1522, -1268, -1857, -1425, -2164, -1537, -2498, -1936, -2531, -2186, -2406, -2192, -2474, -2122, -2288, -1661, -1922, -1425, -2211, -1921, -2598, -2279, -2330, -2207, -2070, -1951, -2145, -1655, -2165, -1597, -2001, -1481, -1745, -1213, -1503, -1120, -1346, -840, -945, -505, -487, -553, -249, -359, 358, 275, 1330, 817, 2232, 1420, 2760, 1975, 3297, 2081, 4161, 2379, 4854, 2803, 4822, 3033, 4755, 3299, 4892, 3128, 4562, 2501, 4015, 2360, 3615, 2112, 2964, 1308, 2060, 499, 1003, -525, -19, -1526, -631, -1833, -1008, -2028, -1533, -2556, -2049, -2951, -2617, -3028, -2917, -2784, -2354, -2245, -1828, -1936, -2041, -1860, -2094, -1503, -1685, -808, -1276, -475, -926, -566, -550, 61, -209, 747, 177, 567, 258, 374, 247, 509, 396, 381, 373, 465, -68, 474, -102, -78, 316, -302, 308, -225, 7, -514, 273, -438, 842, 19, 1371, 305, 1963, 510, 2195, 288, 2390, 195, 3105, 936, 3766, 1559, 4095, 1685, 4272, 1882, 4012, 1962, 3877, 1942, 4287, 2417, 4271, 2917, 3709, 2738, 3200, 2220, 2547, 2045, 1502, 1602, 597, 705, 247, 327, -199, 103, -1328, -833, -2438, -1645, -2839, -2035, -2838, -2516, -3063, -2761, -3146, -2835, -2549, -2688, -1712, -1897, -1780, -1644, -1963, -2030, -1416, -1627, -866, -1038, -543, -1030, 20, -592, 367, 206, 517, 420, 649, 100, 565, -82, 549, 308, 734, 460, 982, 179, 1184, 390, 1021, 661, 610, 264, 422, -66, 622, -123, 1004, -169, 1367, 126, 1500, 518, 1724, 724, 2165, 784, 2485, 803, 2481, 851, 2507, 809, 2778, 933, 2802, 1202, 2422, 1096, 2283, 646, 2023, 279, 1383, -12, 974, -337, 388, -691, -525, -1114, -855, -1335, -1047, -1611, -1727, -2092, -2184, -2478, -2586)
<type 'str'>
86aEAO    (CF
8AFAD59ABG99

Traceback (most recent call last):
  File "myprogram.py", line 409, in listen
    matrix = calculate_levels(matrix, weighting, data, args.chunk, args.sample_rate)
  File "fft.py", line 17, in calculate_levels
    data = unpack("%dh"%(len(data)/2),data)
struct.error: unpack requires a string argument of length 28

此外，来自麦克风的声音被记录并写入test.wav，但是在记录时没有输出。毕竟，如果没有声音输出，我会感到满意。（在麦克风进入声卡之前，我已经将来自麦克风的声音分开了）

Answer 1

另一答案